PDSCH Modulation Order Adaptation for Unlicensed Band LBT
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Solution Overview
Problem
In mobile communication systems, especially in LTE, using unlicensed bands for data transmission poses challenges due to interference from other systems, and existing listen-before-talk (LBT) procedures are inefficient in managing data transmission timing and parameters across subframes, leading to potential data loss and increased complexity.
Innovation Solution
A base station and user equipment system that dynamically adjusts transmission parameters, such as transport block size, modulation and coding schemes, and resource blocks, based on the start timing of data transmission within a subframe, allowing for multiple candidate timings and specific signal transmission to optimize data capacity and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If LBT procedure is used to monitor unlicensed band frequency, then interference with other systems is avoided, but data transmission efficiency is reduced due to additional monitoring overhead and potential data loss
Solution Approach 1:
The base station performs LBT monitoring and determines transmission parameters before the actual data transmission begins. The modulation order for the PDSCH is determined in advance based on whether the PDSCH is transmitted in the first slot or second slot of the subframe, allowing the UE to prepare for reception without waiting for actual transmission, thus reducing overhead and improving efficiency
2Device complexity
If fixed transmission parameters are used across all subframes, then system complexity is reduced, but resource utilization is inefficient due to varying subframe start times
Solution Approach 1:
The transmission parameters, specifically the modulation order, are made dynamic rather than fixed. The modulation order is determined based on the transmission slot position (first slot or second slot) within the subframe, allowing the system to adapt transmission characteristics to the actual subframe structure and start times, thereby improving resource utilization without requiring complex per-subframe parameter management
Data Source
AI summary
A user equipment, method and apparatus receive a PDSCH from a base station and determine a modulation order used in the PDSCH based on whether the PDSCH is transmitted in a second slot out of a first slot and the second slot which configure a subframe.